Use Filebrowser in a node for the Animation-Nodes-Addon
That is actually very simple because I developed a system to simplify tasks like this one.

You just have to call the invokePathChooser function in your drawing code and give it a callback (the name of the function that handles the result). AN will do the rest for your.

class MyNode(...):
    # ...
    def draw(self, layout):
        self.invokePathChooser(layout, "setFilepath", text = "Find File")

    def setFilepath(self, path):
        print(path)